1. Field
The following description relates to a measurement apparatus for measuring thermal insulation performance of a thermal insulator through variation of heat flux measured by a heat flux sensor, and a measurement method using the same.
2. Description of the Related Art
In general, a vacuum insulation panel has excellent thermal insulation performance when compared with existing thermal insulators, and is thus applied to various fields, such as buildings, home appliances, etc. Such a vacuum insulation panel includes a porous inner core member maintaining the shape of the thermal insulator, an outer surface film having gas barrier properties and surrounding the inner core member to maintain a vacuum, and a gas desiccant to maintain the vacuum for a long time. The thermal insulation performance of the vacuum insulation panel is determined according to the degree of vacuum of the inside of the vacuum insulation panel, and when pressure of the inside of the vacuum insulation panel reaches a designated level or more, the thermal insulation performance of the vacuum insulation panel is rapidly lowered. A getter or the desiccant within the vacuum insulation panel suppresses such degradation of the thermal insulation performance caused by increase of the inner pressure of the vacuum insulation panel, and thus the vacuum insulation panel maintains high thermal insulation performance for a long time. There are various factors causing the degradation of the thermal insulation performance of the vacuum insulation panel, and among these factors, the main factor is penetration of gas due to damage to the outer surface film by external impact when the vacuum insulation panel is handled and transported. The outer surface film includes a metal thin film formed of aluminum foil having a thickness of 6-7 μm to prevent gas penetration, an external plastic film to protect the metal thin film, and a low density polyethylene (LDPE) layer serving as a heat fusion layer for manufacturing a pouch. When the outer surface film is torn, gas is instantaneously introduced into the vacuum insulation panel, the vacuum insulation panel is expanded, and thus gas penetration into the vacuum insulation panel is recognized with the naked eye, but if a slow leak occurs, gas penetration is slowly carried out and thus it may be difficult to recognize such gas penetration with the naked eye due to influence of adsorption of the getter or the desiccant.
However, after the vacuum insulation panel has been embedded in a refrigerator or the wall of a building, it may be difficult to replace the vacuum insulation panel with a new one. Particularly, in case of a refrigerator, when a defect of the vacuum insulation panel is detected after the vacuum insulation panel has been embedded in the refrigerator, the entirety of the refrigerator product is discarded. Therefore, necessity of executing a reliability test to check the inner pressure or thermal conductivity of the vacuum insulation panel before mounting of the vacuum insulation panel rises.